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    <p>The key to using <code>tryCatch</code> is realising that it returns an object. If there was an error inside the <code>tryCatch</code> then this object will inherit from class <code>error</code>. You can test for class inheritance with the function <code>inherit</code>.</p> <pre><code>x &lt;- tryCatch(stop("Error"), error = function(e) e) class(x) "simpleError" "error" "condition" </code></pre> <p><strong>Edit:</strong> </p> <p>What is the meaning of the argument <code>error = function(e) e</code>? This baffled me, and I don't think it's well explained in the documentation. What happens is that this argument catches any error messages that originate in the expression that you are <code>tryCatch</code>ing. If an error is caught, it gets returned as the value of <code>tryCatch</code>. In the help documentation this is described as a <code>calling handler</code>. The argument <code>e</code> inside <code>error=function(e)</code> is the error message originating in your code.</p> <hr> <p>I come from the old school of procedural programming where using <code>next</code> was a bad thing. So I would rewrite your code something like this. (Note that I removed the <code>next</code> statement inside the <code>tryCatch</code>.):</p> <pre><code>for (i in 1:39487) { #ERROR HANDLING possibleError &lt;- tryCatch( thing(), error=function(e) e ) if(!inherits(possibleError, "error")){ #REAL WORK useful(i); fun(i); good(i); } } #end for </code></pre> <hr> <p>The function <code>next</code> is documented inside <code>?</code>for`.</p> <p>If you want to use that instead of having your main working routine inside an <code>if</code>, your code should look something like this:</p> <pre><code>for (i in 1:39487) { #ERROR HANDLING possibleError &lt;- tryCatch( thing(), error=function(e) e ) if(inherits(possibleError, "error")) next #REAL WORK useful(i); fun(i); good(i); } #end for </code></pre>
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    1. POskip to next value of loop upon error in R [tryCatch]
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    1. COGreat explanation. Thanks.
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      1. USJosh O'Brien
    2. COThank you for this answer. I originally had avoided `next` like you recommend, but as I thought of more and more errors that could possibly be caught, the code became a tangle of parentheses: as bad or worse than "programming" a series of conditionals inside an Excel cell.
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    3. COWhen I run `?for` the next line is a `+`. (requesting more input)
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